1. Field of the Invention
The present invention relates to a dynamic adding system for memory files shared among hosts, a dynamic adding method for memory files shared among hosts, and a computer-readable medium recording dynamic adding program for memory files shared among hosts for dynamically expanding the available area in shared memory files by dynamically increasing the number of memory files shared in a multi processor system.
2. Description of the Related Art
The Gazette of the Japanese Patent Laid-open No. 370849/1992 describes a technique to alter the size of one shared memory area shared among a plurality of application programs in one host computer. The host computer consists of one shared memory area accessible from a plurality of application programs; a memory management table for managing the shared memory area; a maximum required size determining function, responsive to requests from a plurality of application programs for expansion of the shared memory area, for determining the greatest size of the requested expansions; a memory expanding function for expanding the shared memory area in accordance with the maximum required size; a minimum required size determining function, responsive to requests from a plurality of application programs for compression of the shared memory area, for determining the smallest size of the requested compressions; and a memory compressing function for compressing the shared memory area in accordance with the minimum required size.
However, according to this prior art technique, each of the plurality of application programs does not notify other application programs of the request it issues for shared memory area expansion or compression. As a result, if an application program requests securing of the shared memory area in a desired size, the shared memory size may be already compressed to a size smaller than the desired size to make it impossible for the requesting application program to secure the size it desires. In every such case, the shared memory area should be expanded, entailing the problem that accessing the shared memory area is made extremely inefficient.
Moreover, there is another problem that, where this prior art is to be applied to the management of a plurality of shared memory areas, i.e. If each of a plurality of application programs requests expansion or compression of the plurality of different shared memory areas without notifying other application programs, vast fragmentation will arise in the memory region containing those shared memory areas.